Which will only return results with 'blog' in the URL. This isn't perfect though, as lots of sites don't use that system, but it's a start. Then you can either use those sites directly, or check which sites link to them using software (I use majestic).

If you have access to majestic and Buzzstream then there's a great process for making it a whole lot more efficient. I'm happy to share the process if anyone's interested.

Advanced search operands work like a dream... for competitive research and link building opportunities. Also, personal preference, I like using Pitchbox for link prospecting.

Create valuable content worthy of your audience, find where your ideal site visitor goes "to feed", discover deficiencies in that site (such as inadequate resource pages or broken links to outbound resources, or value add-on to existing content they have produced, make sure you have a healthy balance of non-followed and followed links), and maintain. Building links used to be easy now it involves a lot of communications and relationship building for relative unknowns.

If you're trying to actively build your link profile- I would be happy to compliment what @kazu has to say.

Agreed, having users makes the whole process of segmenting and understanding his audience a million times easier!

However, since he is just getting started he needs to stalk out his competition which have already gotten his intended audiences attention and do what they're doing (content and link building) much better. From my experience this has worked well. Never built something from the ground up, but definitely found unconventional audiences to established product categories and subject material.

Once he starts pulling their traffic, he can refine his messaging and produce something uniquely his own, than go after untapped and unknown audiences.